The invention relates, in general, to a telecommunications network and a method of operating a telecommunications network, and in particular, to a telecommunications network having a service control point for controlling and carrying out intelligent services, and service switching points which, in order to switch service components of intelligent services, each support a predetermined performance level in accordance with a predetermined application protocol.
The invention likewise relates, in particular, to a method for routing an incoming communications link in a telecommunications network of the type mentioned above, in which a service initialization message is sent to the service control point by a first service switching point in the network as a consequence of a call request arriving at it for a communications link to a subscriber in the network who has subscribed to at least one intelligent service which can be activated for incoming calls.
In conjunction with modern telecommunications networks, it is known that, in addition to basic services such as the telephone services and fax services in a telephone network, other connection-oriented services are set up which can be addressed by a subscriber to the network. These other connection-oriented services are referred to as intelligent services in the following text. The network that supports these services is referred to as an intelligent network (IN). The conventional architecture of the intelligent network provides, in addition to network devices having a service switching function, the so-called service switching points or SSP nodes, and service control points (SCP) as devices for controlling and carrying out intelligent additional services in the intelligent network. The service switching nodes and service control nodes are connected to one another via signaling paths.
For mobile radio networks according to the GSM Standard (xe2x80x9cGlobal System for Mobile Communicationxe2x80x9d), a so-called CAMEL platform (xe2x80x9cCustomized Applications for Mobile network Enhanced Logicxe2x80x9d) has been defined in order to allow world-wide use of the service features of the intelligent network. In a mobile radio network, the service switching nodes are normally referred to as M-SSP (xe2x80x9cMobile SSPxe2x80x9d). A specific protocol is in this case used as the xe2x80x9capplication partxe2x80x9d and for the mobile radio network, comprises the CAP protocol (xe2x80x9cCAMEL Application Partxe2x80x9d, see GSM 09.78).
For further information relating to CAMEL and the CAP protocol, reference should be made to the following GSM Standards: GSM 02.78 xe2x80x9cDigital cellular telecommunications system (Phase 2+, Customized Applications for Mobile Network Enhanced Logic (CAMEL) Service Definition (Stage 1);xe2x80x9d GSM 03.78 xe2x80x9cDigital cellular telecommunications system (Phase 2+), Customized Applications for Mobile Network Enhanced Logic (CAMEL Phase) (Stage 2);xe2x80x9d and GSM 09.78 xe2x80x9cDigital cellular telecommunications system (Phase 2+), Customized Applications for Mobile Network Enhanced Logic (CAMEL) CAMEL Application Part (CAP) specification.xe2x80x9d.
The CAP for the first time created a protocol between M-SSP and SCP which offered roaming IN subscribers, that is subscribers who also move beyond the supply area of their home network (HPLMN, xe2x80x9cHome Public Line Mobile Networkxe2x80x9d) into other visited networks (VPLMN, xe2x80x9cVisited Public Line Mobile Networkxe2x80x9d), intelligent services outside their home network as well while making the services available to subscribers in the home network itself. According to GSM 09.78, the CAP protocol provides a fixed set of functions, the so-called Capability Set 1 (CSI). When the CAP protocol was introduced, CAP phase 1, according to the GSM Standard relating to GSM 02.78 xe2x80x9cDigital cellular telecommunications system (Phase 1), Customized Applications for Mobile Network Enhanced Logic (CAMEL) Service Definition (Stage 1);xe2x80x9d GSM 03.78 xe2x80x9cDigital cellular telecommunications system (Phase 1), Customized Applications for Mobile Network Enhanced Logic (CAMEL Phase) (Stage 2);xe2x80x9d and GSM 09.78 xe2x80x9cDigital cellular telecommunications system (Phase 1), Customized Applications for Mobile Network Enhanced Logic (CAMEL) CAMEL Application Part (CAP) specification,xe2x80x9d provided only a subset of the CS1. Therefore, CAP Phase 1 includes only a very limited instruction set of the intended CS1. Using the seven operations implemented in CAP Phase 1 (instead of the 29 CS1), it is not possible to implement complex intelligent services. These services require a more comprehensive set of instructions, such as those that would be available, in particular, from the CS1. In order to implement such an intelligent service, the link to an M-SSP is routed in a known way on the basis of the intermediate exchange signaling process in the ISUP, which M-SSP can manage the dialog with the SCP via an INAP protocol (xe2x80x9cIntelligent Network Application Partxe2x80x9d), since the operational scope of the CS1 is implemented in the INAP protocol. On the other hand, intelligent services that can be implemented within the scope of the CAP Phase 1 are not passed on, but are carried out in the relevant M-SSP.
For intelligent services which are started for outgoing calls from visitor networks, a so-called MOC Scenario (MOC=xe2x80x9cMobile Originating Callsxe2x80x9d), the published, non-prosecuted German Patent Application DE 198 14 162 A1 from the applicant describes a method for information transmission. Data and parameters can be transmitted between SCP and M-SSP, without the range of messages between the switching point associated with the connection of the calling subscriber, the home registers and that of the M-SSP having to be changed from those of the existing CAP and INAP protocols. Accordingly, during a first dialog via CAP of the M-SSP in the visitor network of the calling subscriber with an SCP in the home network of the calling subscriber, all the parameters for the start operation which is carried out, in accordance with the GSM Standard by means of an IDP message (xe2x80x9cInitial Detection Partxe2x80x9d) are temporarily stored and the call is then passed on to an INAP-compatible M-SSP in the home network. A second dialog is set up there via the INAP protocol to the same SCP in which the original parameters of the start operation (IDP message) are found again by means of correlation information (xe2x80x9ccorrelation idxe2x80x9d) which is likewise transmitted so that the originally desired intelligent service can then be started by the INAP-compatible M-SSP.
However, the described MOC solution cannot be directly transferred to the situation where the intelligent service is initiated by the called subscriber, the so-called MTC scenario (MTC=xe2x80x9cMobile Terminating Callsxe2x80x9d, xe2x80x9cincoming callsxe2x80x9d). This is because this would necessitate three dialogs with the SCP. A first connect dialog in accordance with the CAP, protocol to an IMAP-compatible M-SSP, a second connect dialog via the INAP protocol for the purpose of home-register interrogation between the INAP-compatible M-SSP and the home register, as well as a third dialog via the INAP protocol for carrying out operations which are demanded by the service logic, such as charging applications (so-called xe2x80x9capply chargingxe2x80x9d) and routing operations. This would result in considerable signaling traffic. Such a solution therefore, appears to be virtually unacceptable for manufacturers as well as network operators.
In this context, it should be noted that there is no need to pass on incoming calls for an MTC service, provided the relevant mobile radio network is a fully integrated network, in which all switching points support an INAP protocol. For this purpose, suitable administration of the M-SSP nodes on the network can be used to ensure that the INAP protocol is used for an MTC service, although the visitor register and home register of the network in accordance with the GSM Standard support the MAP protocol (Mobile Application Part), and in particular MAP Version 3, and thus offer support for CAP Phase 1. However, networks in which not all the network nodes are INAP-compatible, so-called overlay networks, frequently occur. Thus, in overlay networks, there is no guarantee that the relevant M-SSP can use an INAP protocol where the operational scope of CAP Phase 1 is not sufficient for an MTC service. The discussed MAP protocol is described in more detail in GSM Standard GSM 09.02 (ETS 300 975) xe2x80x9cDigital cellular telecommunications system (Phase 2+), Mobile Application Part specificationxe2x80x9d.
It is accordingly an object of the invention to provide a method and a telecommunications network, which overcomes the above-mentioned disadvantageous of the methods and networks of this type, and which improves the routing of incoming calls for implementing intelligent services.
With the foregoing and other objects in view there is provided, in accordance with the invention, a telecommunications network that includes a plurality of service switching points for switching service components of intelligent services. Each one of the plurality of service switching points has a capacity to support a predetermined performance level in accordance with a predetermined application protocol. A service control point for controlling and carrying out the intelligent services is provided. The service control point is configured to receive, from a first one of the plurality of service switching points, a service initialization message relating to an incoming communications link to a subscriber in the network. The service control point is configured to determine whether the subscriber has subscribed to an intelligent service that can be activated for incoming calls and which exceeds the predetermined performance level of a first one of the plurality of switching points. The service control point is also configured so that if the determination is in the affirmative, the service control point produces a routing address that includes information relating to further routes for establishing a link to a second one of the plurality of service switching points that supports the performance level required for the at least one service and the service control point transmits the routing address to the first one of the plurality of service switching points.
The routing address that is sent to the first service switching node then, in accordance with well-known methods, causes the call to be routed to the second service switching node, which recovers the original subscriber address and continues the process of setting up the call, including the MTC service.
This solution ensures that MTC services are also carried out in overlay networks, without it being necessary to upgrade the service switching nodes. It is particularly advantageous that the routing process involves little additional signaling complexity.
In accordance with an added feature of the invention, the service control point is set up to check the performance levels supported by the service switching points and to select the second service switching point on the basis of subscription information transmitted by the first service switching point relating to the service or services assigned to the subscriber and relating to the associated number or performance levels. This avoids additional signaling between the service control node and a subscriber database for interrogation of the subscriber-specific service data.
In accordance with an additional feature of the invention, the network is in the form of a mobile radio network, and the service switching points each support the CAP protocol or the INAP protocol. In this case, as already explained, the CAP protocol represents a lower performance level, for which the INAP protocol provides an overall scope of service features.
With the foregoing and other objects in view there is provided, in accordance with the invention, a method for routing an incoming communications link in a telecommunications network, which includes providing a telecommunications network with a service control point for controlling and carrying out intelligent services; a plurality of service switching points for switching service components of intelligent services; and a subscriber that has subscribed to at least one intelligent service that can be activated for incoming calls. Each one of the plurality of service switching points is provided with the capacity to support a predetermined performance level in accordance with a predetermined application protocol. The method also includes sending, to a first one of the plurality of service switching points, a call requesting a communications link with the subscriber. In response to the call, a service initialization message is sent from the first one of the plurality of service switching points to the service control point. Subsequently, it is determined whether the at least one service subscribed to by the subscriber exceeds the predetermined performance level of the first one of the plurality of service switching points. The service control point is used to make the determination. If the determination is in the affirmative, the method further includes the following subsequent steps. With the service control point, producing a routing address, using the call address of the subscriber, so that the routing address includes information relating to further routes for establishing a link to a second one of the plurality of service switching points that supports the performance level required for the at least one service subscribed to by the subscriber. With the service control point, transmitting the routing address to the first one of the plurality of service switching points. With the first one of the plurality of service switching points, routing the call to the second one of the plurality of service switching points using the routing address. Finally, with the second one of the plurality of service switching points, switching the at least one service subscribed to by the subscriber.
In accordance with an added mode of the invention, a subscriber database is provided for storing data relating to subscribers registered in the network including data relating to the at least one intelligent service. The subscriber database is also for storing data relating to the predetermined performance level of at least one of the plurality of service switching points. The subscriber database is interrogated with the first one of the plurality of service switching points to obtain information. The information is transmitted from the first one of the plurality of service switching points to the service control point. With the service control point, the predetermined performance level of at least one of the plurality of service switching points is checked. With the service control point, the second one of the plurality of the service switching points is selected dependent upon the data in the subscriber database.
In accordance with an additional mode of the invention, the telecommunications network is a mobile radio network; and each one of the plurality of service switching points is configured to support a protocol selected from the MAP protocol and the INAP protocol.
In accordance with a concomitant mode of the invention, the subscriber database is provided in a mobile radio network.
The advantages of the method according to the invention and of its refinements correspond to what has been described on the basis of the telecommunications network according to the invention.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a telecommunications network and method for routing incoming calls for MTC services, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.